function[c] = ak_cres(prd),
data = load('c:\manoj\temp\thick_sigma_corrected.txt');

AKData = [50800 236 -268 26 0.80 386 -204 26 0.81;...
71600 367 -267 29 0.81 497 -195 29 0.81;...
100900 555 -207 31 0.86 608 -137 31 0.84;...
142300 606 -153 26 0.90 674 -83 26 0.92;...
200600 693 -129 30 0.92 755 -73 30 0.92;...
282900 727 -119 32 0.93 745 -64 32 0.93;...
398900 749 -121 32 0.96 757 -66 37 0.93;...
562400 774 -129 37 0.96 789 -102 42 0.93;...
793000 781 -183 49 0.94 798 -133 50 0.93;...
1118100 810 -244 54 0.94 827 -218 54 0.94;...
1576600 846 -264 59 0.94 857 -243 73 0.93;...
2223000 894 -288 90 0.92 912 -279 100 0.92;...
3134400 910 -264 151 0.85 919 -248 152 0.85;...
4419500 1136 -290 196 0.83 1138 -276 199 0.83;...
6231500 1123 -262 206 0.91 1127 -242 205 0.91;...
8786400 1326 -273 259 0.84 1324 -273 259 0.84;...
12388800 1320 -323 343 0.82 1317 -347 342 0.82];


mu = 4*pi*10^-7;

for i = 1:length(AKData),
    Y = cres(1,60,data(:,1),data(:,2),AKData(i,1));
    wm = sqrt(-1)*mu * 2.0*pi/AKData(i,1); 
    c(i) = -1.0/(wm*Y(1));
end;
semilogx(AKData(:,1),-imag(c)/1000,'k*-');
hold on;
semilogx(AKData(:,1),real(c)/1000,'c*-');

prd = 24*3600;
data = load('c:\manoj\projects\eej-induction\quebec.txt');
data(:,1) = data(:,1)*1e3;
data(:,2) = 1./data(:,2);
Y = cres(1,5,data(:,1),data(:,2),prd);
wm = sqrt(-1)*mu * 2.0*pi/prd;
c1 = -1.0/(wm*Y(1));
